1. Field of the Invention
The embodiments discussed herein relate to a gate driver that drives a gate of a switching element.
2. Background of the Related Art
A power converter, such as an inverter, is provided with a bridge circuit in which switching elements (such as a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT)) are connected in series.
The bridge circuit is configured such that a switching element of a high electric potential side and a switching element of a low electric potential side are connected in series and that a load is connected to a midpoint electric potential. The gates of the switching elements are driven to turn on and off the switching elements in order to drive the load.
As a conventional technology related to driving a gate of a switching element, there is proposed a technology that detects a gate voltage value of a switching element and changes a gate drive resistance or drive current on the basis of the detected gate voltage value (Japanese Laid-open Patent Publication No. 2008-92663).
In the conventional technology, when the gate of the switching element is driven, voltage of a high electric potential or a low electric potential is applied from a direct-current power supply via a resistor, in order to control and drive the gate of the switching element by the electric current that flows through the resistor.
However, this gate driving controls charging and discharging of a parasitic capacitance of the switching element via the resistor, and thus is unable to set an arbitrary voltage gradient for an instantaneous voltage value at a rising edge and a falling edge of the gate voltage of the switching element.
Hence, for example, it is difficult to adjust the voltage gradient to suppress the rise of the surge voltage generated when the switching element is turned off and the surge current that occurs when the switching element is turned on or to reduce a switching loss. Therefore, the quality of the power converter is deteriorated.